Extend content::DesktopMediaID to allow Aura windows as capture sources.

The new DesktopCaptureID::TYPE_AURA_WINDOW will be used for
Desktop Capture API to tell the content layer to capture Aura windows
instead of native screen/windows.

Also moved DesktopCaptureID to content/public/browser from
content/public/common - it doesn't make sense to use that class in the renderer.

BUG=295102
R=ben@chromium.org, cpu@chromium.org, hshi@chromium.org

Review URL: https://codereview.chromium.org/100743003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241031 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241031
[Android] Fix crash on opening context menu without default search engine.

BUG=278480
NOTRY=true

Review URL: https://codereview.chromium.org/115323006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241032 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241032